Neuropeptide modulation of the immune response in gut associated lymphoid tissue

Luminal administration ex vivo of a live Lactobacillus species moderates mouse jejunal motility within minutes

Gut commensals modulate host immune, endocrine, and metabolic functions. They also affect peripheral and central neural reflexes and function. We have previously shown that daily ingestion of Lactobacillus reuteri (LR) for 9 d inhibits the pseudoaffective cardiac response and spinal single-fiber discharge evoked by visceral distension, and decreases intestinal motility and myenteric AH cell slow afterhyperpolarization (sAHP) by inhibiting a Ca-activated K (IK(Ca)) channel. We tested whether luminal LR could acutely decrease motility in an ex vivo perfusion model of naive Balb/c jejunum. Live LR dose dependently decreased motor complex pressure wave amplitudes with 9- to 16-min onset latency and an IC(50) of 5 × 10(7) cells/ml Krebs. Heat-killed LR or another live commensal, Lactobacillus salivarius, were without effect. The IK(Ca) channel blocker TRAM-34, but neither the opener (DCEBIO) nor the hyperpolarization-activated cationic channel inhibitor ZD7288 (5 μM) (or TTX 1 μM), mimicked the LR effect on motility acutely ex vivo. We provide evidence for a rapid, strain-specific, dose-dependent action of a live Lactobacillus on small intestinal motility reflexes that recapitulates the long-term effects of LR ingestion. These observations may be useful as a first step to unraveling the pathways involved in bacteria to the nervous system communication.

Neuroendocrine regulation of salivary IgA synthesis and secretion: implications for oral health

Secretory immunoglobulin A (S-IgA) represents the main adaptive immune mechanism in the oral cavity. The regulation of secretion and synthesis of S-IgA is not only dependent on prior antigenic stimulation, but is also under strong neuroendocrine control. Thus, alterations in neuroendocrine functioning (such as induced by stress, exercise, pregnancy, menstrual cycle, and pharmacological interventions) may affect salivary IgA levels. This review deals with the neuroendocrine regulation of synthesis and secretion of salivary IgA and its potential role in the maintenance of oral health.

Paradoxical exacerbation of psoriasis in AIDS: proposed explanations including the potential roles of substance P and gram-negative bacteria

Psoriasis, a TH1-induced disorder, is not more common in human immunodeficiency virus (HIV) infection than in the general population. However, it may appear for the first time or pre-existing psoriasis may worsen and be difficult to treat in HIV disease. The paradoxical exacerbation of psoriasis in AIDS has not been fully explained. Various explanations have been proposed including (a) the reduction of Langerhans' cells (LCs) in HIV disease, (b) the direct epidermal proliferative effect of HIV, (c) the altered cytokine profile in HIV disease, (d) HIV-induced macrophage nitric oxide (NO) production, (e) the increased CD8/CD4 T-cell ratio in HIV infection and (f) the increased colonization of skin by Staphylococcus aureus. However, the observations that (a) LCs cells play an important role in the pathogenesis of psoriasis and a variety of topical and systemic psoriasis treatments cause a reversible decrease in LC function, (b) psoriasis may improve in end-stage HIV infection, (c) overproduction of some TH2 cytokines and underproduction of IL-2 in HIV infection, and (d) the presence of NO favors a TH2 response over a TH1 response make the first four explanations difficult to interpret. Since psoriasis is exacerbated in HIV infection possibly due to the increased staphylococcal colonization, and psoriatic keratinocytes could aggravate HIV infection through production of TNF-alpha, it could be reasoned that in HIV-positive psoriatics a strong vicious cycle is present between the degree of immune deficiency and the staphylococcal colonization, explaining the poor prognosis of both AIDS and psoriasis in these patients. With reference to the studies which indicate significant involvement of substance P (SP) in the pathogenesis of psoriasis and on the other hand increased release of this agent by HIV-infected immune cells it is proposed that SP plays an important role in creating the paradox. Since in HIV-positive psoriatics the source of SP is largely immune cells not neurons, capsaicin, which exerts its action selectively on a subpopulation of neurons, could not be of significant therapeutic value. As SP significantly enhances HIV-1 replication in latently infected immune cells, psoriatic lesions, being heavily infiltrated with immune cells and having high concentrations of SP, could serve as high HIV-replication foci, with the resultant rapid progression of the infection towards AIDS. Additionally, given that lipopolysaccharide is supposed to exacerbate psoriasis, increase of gram-negative infections or cutaneous colonization with these organisms in AIDS may partly explain the paradox. Understanding the HIV-induced immunodysregulation that is associated with psoriasis in some HIV-seropositive patients may assist in the delineation of the immunopathogenesis of the disease in HIV-seronegative psoriatics.

Peptide receptors as molecular targets for cancer diagnosis and therapy

During the past decade, proof of the principle that peptide receptors can be used successfully for in vivo targeting of human cancers has been provided. The molecular basis for targeting rests on the in vitro observation that peptide receptors can be expressed in large quantities in certain tumors. The clinical impact is at the diagnostic level: in vivo receptor scintigraphy uses radiolabeled peptides for the localization of tumors and their metastases. It is also at the therapeutic level: peptide receptor radiotherapy of tumors emerges as a serious treatment option. Peptides linked to cytotoxic agents are also considered for therapeutic applications. The use of nonradiolabeled, noncytotoxic peptide analogs for long-term antiproliferative treatment of tumors appears promising for only a few tumor types, whereas the symptomatic treatment of neuroendocrine tumors by somatostatin analogs is clearly successful. The present review summarizes and critically evaluates the in vitro data on peptide and peptide receptor expression in human cancers. These data are considered to be the molecular basis for peptide receptor targeting of tumors. The paradigmatic peptide somatostatin and its receptors are extensively reviewed in the light of in vivo targeting of neuroendocrine tumors. The role of the more recently described targeting peptides vasoactive intestinal peptide, gastrin-releasing peptide, and cholecystokinin/gastrin is discussed. Other emerging and promising peptides and their respective receptors, including neurotensin, substance P, and neuropeptide Y, are introduced. This information relates to established and potential clinical applications in oncology.

Somatostatin inhibits intestinal mucosal mast cell degranulation in normal conditions and during mast cell hyperplasia

Several studies demonstrate that intestinal mucosal mast cells (IMMC) are modulated by nervous reflexes as well as by intraluminal content. We recently demonstrated that peptones, such as ovalbumin hydrolysate (OVH), induce the release of rat mast cell protease II (RMCP II), indicating IMMC degranulation. The response is due to complex neuroendocrine reflexes. Somatostatin (SS) and its analogues have been used as potential treatments for inflammation in other body systems with contradictory results. The aim of this study was to evaluate if somatostatin could contribute to the reduction of intestinal mucosal mast cell degranulation. Anesthetized rats were prepared for duodenal perfusion and mast cell activation was measured by analysis of RMCP II concentration in the duodenal perfusate. Somatostatin significantly decreased RMCP II concentration in both nonstimulated conditions and after ovalbumin hydrolysate perfusion. However, when somatostatin was given previously to OVH, the peptone still induced a slight increase of RMCP II. Similar effects were observed in animals previously treated with capsaicin. These protocols were repeated in animals infected with Trichinella spiralis, which induces mucosal mast cell hyperplasia. In these cases, somatostatin blocked the effect of OVH, thus, preventing an increase in RMCP II concentration. Fresh frozen tissue sections from the duodenum were processed in an attempt to demonstrate the presence of SS receptors in mast cells using immunofluorescence and Fluo-peptide labeling techniques. Confocal images from duodenum specimens demonstrate the existence of SS receptors in positive cells for RMCP II. Taken together, these results indicate that somatostatin diminishes mast cell activity and in consequence could prevent the intestinal responses to mast cell hyperplasia.

Intradermal skin test reactivity to histamine and substance P is blunted in dogs with atopic dermatitis

Skin reactivity to intradermal injections (0.1, 0.5 and 1 nM) of substance P (SP) was evaluated in 20 clinically normal dogs and 20 dogs with atopic dermatitis (AD). Saline and histamine were used as negative and positive controls, respectively. Wheal diameters were measured. Reactions were evaluated for erythema and induration and a subjective score, on a scale from 0 to 4+, was given. Evaluations were performed at 3, 5, 10, 15 and 30 min after the injections. Wheal diameters for histamine and SP injections were significantly smaller in dogs with AD compared with clinically normal dogs. In both groups, reactions to the various concentrations of SP were not significantly different from each other and were always smaller than histamine reactions. Erythema was not seen with SP injections. In addition, subjective scores for SP injections were significantly lower in dogs with AD compared with controls. The results of this study are similar to those reported in human medicine, where a role for SP in AD is proposed and desensitization of receptors to both SP and histamine is hypothesized. Further studies are needed to investigate the role of SP in the pathogenesis of canine AD.

Consequences of intestinal inflammation on the enteric nervous system: neuronal activation induced by inflammatory mediators

The ENS is responsible for the regulation and control of all gastrointestinal functions. Because of this critical role, and probably as a consequence of its remarkable plasticity, the ENS is often relatively well preserved in conditions where the architecture of the intestine is seriously disrupted, such as in IBD. There are structural and functional changes in the enteric innervation in animal models of experimental intestinal inflammation and in IBD. These include both up and down regulation of transmitter expression and the induction of new genes in enteric neurons. Using Fos expression as a surrogate marker of neuronal activation it is now well established that enteric neurons (and also enteric glia) respond to inflammation. Whether this "activation" is limited to a short-term functional response, such as increased neuronal excitability, or reflects a long-term change in some aspect of the neuronal phenotype (or both) has yet to be firmly established, but it appears that enteric neurons are highly plastic in their response to inflammation.

Localization of Receptors for Vasoactive Intestinal Peptide, Somatostatin, and Substance P in Distinct Compartments of Human Lymphoid Organs

Regulatory peptides, such as vasoactive intestinal peptide (VIP), somatostatin (SS), or substance P (SP), are considered to play a role in immune regulation. To localize the targets of these peptides in the human immune system, their receptors have been evaluated with in vitro receptor autoradiography in lymph nodes, tonsils, appendix, Peyer's patches, spleen, and thymus. The three peptide receptors were detected in all lymphoid tissues tested, but, unexpectedly, usually in distinct compartments. In lymph nodes, palatine tonsils, vermiform appendix, and Peyer's patches, VIP receptors were found in the CD3 positive zone around lymphoid follicles; SS receptors in the germinal centers of secondary follicles; and SP receptors mainly in interfollicular blood vessels. In the spleen, VIP receptors were detected in periarterial lymphatic sheaths, SS receptors in the red pulp, and SP receptors in the central arteries. In the thymus, VIP receptors were present in cortex and medulla, SS receptors in the medulla, and SP receptors in blood vessels. For comparison, cholecystokinin (CCK)-A and -B receptors were not demonstrated in any of these tissues. These results suggest a strong compartmentalization of the three peptide receptors in human lymphoid tissues and represent the molecular basis for the understanding of a very complex and interactive mode of action of these peptides.

Innervation of melanocytes in human skin

Communication between the nervous system and epidermal melanocytes has been suspected on the basis of their common embryologic origin and apparent parallel involvement in several disease processes, but never proven. In this study, confocal microscopic analysis of human skin sections stained with antibodies specific for melanocytes and nerve fibers showed intraepidermal nerve endings in contact with melanocytes. This intimate contact was confirmed by electron microscopy, which further demonstrated thickening of apposing plasma membranes between melanocytes and nerve fibers, similar to synaptic contacts seen in nervous tissue. Since many intraepidermal nerve fibers are afferent nerves that act in a "neurosecretory" fashion through their terminals, cultured human melanocytes were stimulated with calcitonin gene-related peptide (CGRP), substance P, or vasoactive intestinal peptide, neuropeptides known to be present in cutaneous nerves, to examine their possible functions in the epidermal melanin unit. CGRP increased DNA synthesis rate of melanocytes in a concentration- and time-dependent manner. Cell yields after 5 d were increased 25% compared with controls maintained in an otherwise optimized medium. Furthermore, stimulation by CGRP induced rapid and dose-dependent accumulation of intracellular cAMP, suggesting that the mitogenic effect is mediated by the cAMP pathway. These studies confirm and expand a single earlier report in an animal model of physical contact between melanocytes and cutaneous nerves and for the first time strongly suggest that the nervous system may exert a tonic effect on melanocytes in normal or diseased human skin.

Neuropeptides and general neuronal marker in psoriasis--an immunohistochemical study

Nerve fibres immunoreactive to antibodies to vasoactive intestinal polypeptide (VIP) and substance P (SP) were increased in lesional psoriatic skin when assessed semiquantitatively. Biopsies from psoriatic plaques on the arm were studied in 13 patients and compared with biopsies from non-lesional areas (in three of the same psoriatic subjects) and from normal skin in seven non-psoriatic controls. Immunohistochemical methods were used on cryocut skin sections to demonstrate the neuropeptides SP, VIP, calcitonin gene-related peptide and neuropeptide Y, and the general neuronal marker protein gene product (PGP) 9.5. The immunofluorescence was examined by semiquantitative and, for PGP 9.5, by quantitative methods. VIP reactive nerve fibres were increased at areas of eccrine sweat glands throughout the dermis, at the dermo-epidermal junction, and in the epidermis, in psoriasis lesional skin. SP reactive nerve fibres were increased at the dermo-epidermal junction, where the nerves ran parallel with and perpendicularly through the junction. PGP 9.5 reactive nerve fibres showed an increase at the dermo-epidermal junction, in the papillary dermis, and at the eccrine sweat glands in lesional psoriatic skin but not in non-lesional, or in control skin. These findings support the hypothesis that neuropeptides may be involved in the pathogenesis of psoriasis.

Importance of vasoactive intestinal peptide and somatostatin for fluid losses in small-bowel obstruction

BACKGROUND

Previous observations have shown vasoactive intestinal peptide (VIP) to be an important secretagogue in the gut, whereas somatostatin has been reported to inhibit VIP release and fluid secretion.

METHODS

The possible role of VIP as mediator of the inflammation and fluid losses in obstructive ileus was investigated in vivo and in a chronic rat model with thread ligation of the jejunum. Extravasated Evans blue (Eb)-stained albumin was quantified by spectrophotometry. Net fluid secretion was measured by a gravimetric technique. VIP antiserum was used to inhibit the effects of endogenous VIP. A somatostatin analogue, octreotide, was used to inhibit the release of VIP.

RESULTS

Results showed a pronounced plasma Eb-albumin extravasation in the wall of the obstructed gut, which was significantly inhibited by VIP antiserum (p < 0.05) or octreotide (p < 0.01). Obstruction of the jejunum resulted in net fluid secretion that was significantly reduced by administration of octreotide (p < 0.01) or VIP antiserum (p < 0.05). Net fluid secretion in control animals remained constant.

CONCLUSIONS

These findings suggest that VIP is an important mediator of the pathophysiology in mechanical intestinal obstruction and that somatostatin may be involved in the endogenous control of fluid losses.

The significance of the human endolymphatic sac and its possible role in Menière's disease

Modern immunohistochemical methods allow a functional characterization of the human endolymphatic sac (ES) and its associated cell populations. The currently available immunohistochemical data of the extraosseous part of the human ES support the assumption that the epithelium is metabolically active and capable of both secretion and adsorption. The reactivity of the epithelial cells with antibodies against neuroendocrine antigens imply a paracrine activity of the human ES. Further results provide evidence for a possible role of the human ES in inner ear immune defence and indicate a putative functional relationship of the human ES to the common mucosa-associated immune system (MALT).

Somatostatin and the immune and haematopoetic system; a review

SS-R and SS have been demonstrated in non-pathological and pathological lymphoid tissue and may play a regulatory, mostly inhibitory, role in the immune response. SS is produced by lymphocytes and monocytes which suggests an autocrine or paracrine regulatory role, but SS may be released as well by nerve endings. It can therefore be hypothesized that apart from a role of SS in local, immunomodulation of cells belonging to the immune system, a second pathway exists in which this peptide exerts its effects via neuroendocrine modulation of the immune response which might represent a direct regulatory relation between the nervous and the immune system. The presence of SS-R in lymphoid neoplasm cells and in diseases involving activated mononuclear leukocytes allows the visualization of these diseases using octreotide scintigraphy. This technique may be used in the evaluation of the spread of these diseases and to monitor their response to therapy. Moreover, the presence of SS-R in immune diseases warrants studies on the efficacy of treatment with octreotide of patients suffering from these diseases.

Neonatal capsaicin pretreatment suppresses intramedullary inflammation in adjuvant-induced spondylitis

In order to investigate the proposed involvement of neuropeptides in musculoskeletal inflammation we pretreated rats, in an adjuvant spondylitis model, with capsaicin, a neurotoxin. Immunohistochemistry showed that administration of capsaicin to newborn rats depleted irreversibly the neuropeptide, substance P. Elimination of capsaicin-sensitive fibres by the neonatal injection of capsaicin did not suppress the peridiscitis of rats in which adjuvant spondylitis was induced at 7 weeks of age. However, elimination of capsaicin-sensitive fibres did suppress the inflammation usually seen in the bone marrow. We speculate that this intramedullary inflammation is normally induced or sustained by capsaicin-sensitive fibres.

Topical capsaicin administration protects against trinitrobenzene sulfonic acid-induced colitis in the rat

We used the [3H]resiniferatoxin binding assay to demonstrate for the first time the existence of vanilloid receptors in the rat colon and to explore their expression during trinitrobenzene sulfonic acid-induced colitis. Membranes obtained from control colon bound [3H]resiniferatoxin with an affinity of 3 nM; the receptor density was 450 fmol/mg protein or 9 fmol/mg wet weight. Capsaicin and capsazepine, a competitive antagonist of capsaicin, inhibited specific resiniferatoxin binding with Ki values of 3 microM and 0.1 microM, respectively. Trinitrobenzene sulfonic acid induced a very rapid ulceration in the colon: 1 h after treatment 90% of the colon showed ulcerative damage. Coadministration of 640 microM capsaicin diminished the ulcerative effect of trinitrobenzene sulfonic acid to 64% when examined 1 h after trinitrobenzene sulfonic acid challenge; however, this protective action was lost 23 h later. Colon samples obtained 4 h, 24 h, and 1 week after trinitrobenzene sulfonic acid challenge bound resiniferatoxin, capsaicin, and capsazepine with affinities similar to those of control samples. The receptor density remained at an essentially constant level when expressed in fmol/mg protein but, in keeping with the increased wet weights, showed a reduction when expressed in fmol/mg wet weight. We conclude that acute capsaicin administration protects against the ulcerative action of trinitrobenzene sulfonic acid, most likely via the release of protective neuropeptides from capsaicin-sensitive nerve endings. The loss of this protective action is presumably due to a depletion of the protective neuropeptides rather than to a loss of vanilloid (capsaicin) receptors.

Effects on local blood flux of acupuncture stimulation used to treat xerostomia in patients suffering from Sjögren's syndrome

Twenty-one patients with Sjögren's syndrome were given four different kinds of acupuncture stimulation, at acupuncture points previously used to treat xerostomia. The local blood flux in the skin overlying the parotid gland was measured with laser Doppler flowmetry before, during and after the acupuncture stimulation. The results showed that the local blood flux increased significantly during and after both manual acupuncture and low-frequency (2 Hz) electro-acupuncture as compared with superficial acupuncture. These results indicate that acupuncture induced an increase in the local blood flux which was more pronounced for those patients who had previously reacted with increased salivary flow to acupuncture.

Substance P levels are decreased in lesional skin of atopic dermatitis

There is increasing evidence that neuropeptides (NP) such as substance P (SP) and vasoactive intestinal polypeptide (VIP) are involved in the pathogenesis of atopic dermatitis (AD). Vasoactive intestinal polypeptide levels were found to be significantly elevated in lesional skin of AD as compared to controls. We evaluated by radioimmunoassay the SP content in whole skin homogenates from chronic lichenified lesions of patients with AD. The levels of SP were significantly decreased in lesional skin from AD patients as compared to control skin (0.25 +/- 0.03 vs. 0.97 +/- 0.24 pmol/g tissue, p < 0.01). The diminished SP levels as opposed to increased VIP concentrations could be consistent with different roles of these NP as modulatory agents in the mechanisms associated with AD.

Cyclic AMP response element-binding protein and the catalytic subunit of protein kinase A are present in F9 embryonal carcinoma cells but are unable to activate the somatostatin promoter

The cyclic AMP (cAMP) response elements (CREs) of the somatostatin and vasoactive intestinal peptide (VIP) promoters contain binding sites for CRE-binding protein (CREB) that are essential for cAMP-regulated transcription. Using F9 embryonal carcinoma cells, we show that the somatostatin and VIP promoters exhibit a differentiation-dependent cAMP response, demonstrating that these promoters are regulated by transcription factors that become active during differentiation. Lack of cAMP responsiveness of the somatostatin promoter in undifferentiated cells is not due to the absence of known positive-acting factors (the catalytic subunit of protein kinase A [cPKA] and CREB) or a general inhibition of protein kinase A activity. Since overexpression of exogenous cPKA and CREB is sufficient to activate the somatostatin promoter in undifferentiated cells, these findings suggest that a negative factor(s) represses endogenous cPKA and CREB. In contrast to their effects on somatostatin, exogenous CREB and cPKA do not activate the VIP promoter. Thus, despite coregulation during differentiation and the ability to bind CREB, the somatostatin and VIP promoters are not coordinately activated by CREB in undifferentiated F9 cells.

Cyclic AMP response element-binding protein and the catalytic subunit of protein kinase A are present in F9 embryonal carcinoma cells but are unable to activate the somatostatin promoter

The cyclic AMP (cAMP) response elements (CREs) of the somatostatin and vasoactive intestinal peptide (VIP) promoters contain binding sites for CRE-binding protein (CREB) that are essential for cAMP-regulated transcription. Using F9 embryonal carcinoma cells, we show that the somatostatin and VIP promoters exhibit a differentiation-dependent cAMP response, demonstrating that these promoters are regulated by transcription factors that become active during differentiation. Lack of cAMP responsiveness of the somatostatin promoter in undifferentiated cells is not due to the absence of known positive-acting factors (the catalytic subunit of protein kinase A [cPKA] and CREB) or a general inhibition of protein kinase A activity. Since overexpression of exogenous cPKA and CREB is sufficient to activate the somatostatin promoter in undifferentiated cells, these findings suggest that a negative factor(s) represses endogenous cPKA and CREB. In contrast to their effects on somatostatin, exogenous CREB and cPKA do not activate the VIP promoter. Thus, despite coregulation during differentiation and the ability to bind CREB, the somatostatin and VIP promoters are not coordinately activated by CREB in undifferentiated F9 cells.

Substance P Is Diminished and Vasoactive Intestinal Peptide Is Augmented in Psoriatic Lesions and These Peptides Exert Disparate Effects on the Proliferation of Cultured Human Keratinocytes

An involvement of neurogenic components in the pathogenesis of psoriatic lesions has been suggested and neuropeptides are thought to play a modulatory role in cutaneous inflammation. In this study, we evaluated the immunoreactivity of the neuropeptides vasoactive intestinal polypeptide (VIP) and substance P (SP) in the skin of patients with chronic plaque psoriasis, by immunohistochemistry and radioimmunoassay. No differences were observed, by immunohistochemistry, in the expression and localization of VIP and SP between psoriatic and normal skin. Using the radioimmunologic technique on whole skin homogenates, VIP levels were significantly increased in psoriatic lesions as compared to normal skin. By contrast, SP levels were significantly lower in lesional and non-lesional psoriatic skin than in normal skin. In addition, we examined the effect of VIP and SP on the proliferation of cultured normal human keratinocytes. VIP (1-28) (1 nM-1 microM) as well as VIP fragments (10-28) (1 nM-1 microM) and (22-28) (1 nM-1 microM) stimulated the proliferation of keratinocytes in a dose-dependent manner, whereas the VIP fragment (1-12) (1 nM-1 microM) was ineffective. The VIP antagonist (N-Ac-Tyr1, D-Phe2)-GRF (1-29)-NH2 (0.1 microM) significantly inhibited the VIP effect on keratinocytes. On the other hand, SP (0.1 microM) not only failed to stimulate keratinocyte growth, but also blocked the VIP-induced stimulation of these cells. The imbalance of cutaneous VIP and SP and their disparate effects on the proliferation of normal human keratinocytes in culture would suggest that these peptides are involved in the pathogenesis of psoriasis and may exert different modulatory activities in the mechanisms underlying the psoriatic lesion.

Immunohistochemical characterization of the human endolymphatic sac and its associated cell populations

The use of monoclonal and polyclonal antibodies as specific markers for the localization of tissue constituents in situ allows the characterization of cells according to their state of differentiation and the detection of cellular antigens related to the function of cells and tissues. Our studies focus on the immunohistochemical characterization of the human endolymphatic sac (ES) and its associated cell populations. A panel of 37 monoclonal and polyclonal antibodies were used on frozen sections and fixed material from 64 ES of 32 persons without any clinically known inner ear disorders. The ES were removed at the time of autopsy; case histories were available. The results of our studies on the extraosseous part of the human ES support the assumption that the epithelium is metabolically active and capable of both secretion and absorption. The reactivity of the epithelial cells with antibodies against neuron specific enolase, chromogranin and somatostatin, respectively, implies a paracrine activity of the ES. Further results obtained with antibodies specific for cells of the immune system indicate a possible role of the human ES in the inner ear immune defence and a functional relationship of the ES to the common mucosa-associated immune system.

Protecting effects of vasoactive intestinal polypeptide on lymphocytes against metal toxicity

The hormonal neuropeptides calcitonin gene-related peptide (CGRP), cholecystokinin (CCK), neuropeptide Y (NPY) and vasoactive intestinal peptide (VIP), were investigated for a potential protective effect on thymocytes after a toxic dose of nickel sulfate, giving an inhibition of DNA synthesis. There was a statistically significant increase in the synthesis of DNA from the level caused by nickel sulfate, with VIP, 10(-4)-10(-5) mol/l, while the slightly stimulating effects obtained with CGRP, CCK and NPY, were statistically non-significant. This indicates that VIP, at least as pharmacological concentrations, might have protective effects on lymphocytes against metal toxicity.

Isolation and characterisation of the human lung NK-1 receptor cDNA

Functional cDNA clones for human NK-1 receptor were isolated from human lung RNA using the polymerase chain reaction (PCR). We have screened a human cosmid library and isolated a clone which appeared to contain the entire NK-1 receptor gene. From the published rat NK-1 receptor cDNA sequence we designed primers within the protein coding sequence, but outwards towards both the 5' and 3' ends of the putative human protein sequence. By this method we derived DNA sequence from the 3' end of the human gene. In order to determine the 5' end of the gene we used a PCR based method called Rapid Amplification of cDNA Ends (RACE). From the derived human sequences amplimers were designed upstream of the ATG initiation codon and downstream of the stop codon. The entire cDNA was obtained by RNA-PCR from human lung RNA. The sequence obtained was 407 amino acids in length, encoding an open-reading frame that was highly homologous to the rat NK-1 receptor cDNA (89%). The entire human cDNA was then cloned into a mammalian expression vector and mRNA was synthesized by in vitro transcription. Applications of tachykinins caused membrane current responses in Xenopus oocytes injected with the in vitro synthesized mRNA. The most potent of the three tachykinin peptides tested was Substance P. The human NK-1 receptor gene has been mapped to chromosome 2 using the polymerase chain reaction to specifically amplify the human sequence in hamster/human hybrid DNA and also in mouse/human monochromosome hybrids.

Immunoregulators in the nervous system

The nervous system, through the production of neuroregulators (neurotransmitters, neuromodulators and neuropeptides) can regulate specific immune system functions, while the immune system, through the production of immunoregulators (immunomodulators and immunopeptides) can regulate specific nervous system functions. This indicates a reciprocal communication between the nervous and immune systems. The presence of immunoregulators in the brain and cerebrospinal fluid is the result of local synthesis--by intrinsic and blood-derived macrophages, activated T-lymphocytes that cross the blood-brain barrier, endothelial cells of the cerebrovasculature, microglia, astrocytes, and neuronal components--and/or uptake from the peripheral blood through the blood-brain barrier (in specific cases) and circumventricular organs. Acute and chronic pathological processes (infection, inflammation, immunological reactions, malignancy, necrosis) stimulate the synthesis and release of immunoregulators in various cell systems. These immunoregulators have pivotal roles in the coordination of the host defense mechanisms and repair, and induce a series of immunological, endocrinological, metabolical and neurological responses. This review summarizes studies concerning immunoregulators--such as interleukins, tumor necrosis factor, interferons, transforming growth factors, thymic peptides, tuftsin, platelet activating factor, neuro-immunoregulators--in the nervous system. It also describes the monitoring of immunoregulators by the central nervous system (CNS) as part of the regulatory factors that induce neurological manifestations (e.g., fever, somnolence, appetite suppression, neuroendocrine alterations) frequently accompanying acute and chronic pathological processes.

Substance P innervation of spleen in rats: nerve fibers associate with lymphocytes and macrophages in specific compartments of the spleen

We investigated the distribution of SP+ nerve fibers in the spleen of adult male Fischer 344 rats. SP+ nerve fibers entered the spleen with the splenic artery in the hilar region, arborized along the venous sinuses, and extended from these larger plexuses into trabeculae and the surrounding red pulp. In the white pulp, SP+ nerve fibers were found in the marginal zone, and in the outer regions of the PALS among T lymphocytes. No SP+ nerve fibers were observed in association with the splenic capsule, the central arteries of the white pulp, or the follicles. SP levels in rat spleen were 5.7 +/- 0.4 ng/g wet wt. On the basis of the present findings of SP presence in nerve fibers in the spleen, and published evidence for SP receptors on lymphocytes and macrophages, we suggest that SP derived from nerve fibers in the spleen can act as a neurotransmitter with cells of the immune system as targets. These SP nerve fibers may be an important neural link between the nervous system and the immune system and may participate in modulation of immune reactivity and inflammatory responses.

Skin levels of vasoactive intestinal polypeptide in atopic dermatitis

Atopic dermatitis (AD) can be exacerbated by various factors, including emotional stress, scratching and sweating. The aim of the present study was to evaluate the hypothesis that the inflammatory reaction in AD is also neurogenic. For this purpose, the levels of vasoactive intestinal polypeptide were measured radioimmunologically in whole-tissue homogenates of lesional skin of 13 patients with atopic dermatitis. Radioimmunoassay was performed using an antiserum, AH78, recognizing the carboxy-terminal fragment vasoactive intestinal polypeptide (22-28). Vasoactive intestinal polypeptide immunoreactivity was detected in relatively low amounts in control skin (0.428 +/- 0.08 pmol/g tissue), whereas a marked increase in the peptide was observed in lesional skin of patients with atopic dermatitis (5.62 +/- 1.25 pmol/g tissue). These results seem to suggest that vasoactive intestinal polypeptide could have a pathogenetic relevance in skin lesions of atopic dermatitis.

Vasoactive intestinal peptide (VIP) activation of nuclear protein kinase C in purified nuclei of rat splenocytes

We have examined the actions of vasoactive intestinal peptide (VIP) and certain other known immune modulators on a nuclear pool(s) of protein kinase C (PKC) in isolated rat splenocyte nuclei. Rat splenocyte nuclei pure by enzymatic and electron microscope criteria demonstrated a time- and concentration-dependent activation of nuclear PKC (nPKC) by VIP. A biphasic pattern of three bell-shaped curves was observed with peak phosphorylation at 10(-15), 10(-9) and 10(-6)M VIP. The phosphorylation of endogenous nuclear substrates was characterized as a PKC-mediated event by use of three known PKC inhibitors, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), sphingosine, and staurosporine, which produced similar phosphate incorporation measurements. Also, this activity was blocked with the addition of a monoclonal antibody to PKC. Inhibitors of the ability of VIP to activate nPKC included somatostatin, 8-bromo-cAMP, peripheral benzodiazepine receptor modulators, and the PKC inhibitors, sphingosine and staurosporine. These data have direct relevance to our knowledge of cell-mediated immunity.

Neuropeptides in skin from patients with atopic dermatitis: an immunohistochemical study

The distribution and localization of several neuropeptides were investigated in the lichenified lesions of 11 patients with atopic dermatitis using indirect immunofluorescence. Substance P-positive nerve fibres were observed in most of the cases of atopic dermatitis, but not in normal controls. Somatostatin immunoreactive nerves were not found in the skin of atopic dermatitis, whereas a normal pattern of immunoreactivity could be detected in most of the healthy subjects. Neuropeptide Y-positive dendritic epidermal cells were observed in lesional skin from patients with atopic dermatitis, but not in controls. Calcitonin gene-related peptide and vasoactive intestinal polypeptide immunoreactivity in patients with atopic dermatitis did not differ from that in healthy subjects. With galanin antiserum a diffuse intracellular staining was observed in the epidermis of both atopic patients and controls, while no positive staining was found with either neurotensin or neurokinin A antibodies in either group. These findings suggest a possible involvement of some neuropeptides in the pathomechanisms of atopic dermatitis.

Immunomodulators and feeding regulation: a humoral link between the immune and nervous systems

Cells of the nervous and immune systems have specific receptors for humoral substances that originate in both systems. These elements establish a bidirectional information exchange network between the nervous and immune systems. In particular, neuroregulators (neurotransmitters and neuromodulators) can modulate specific immune system function(s) and immunoregulators (immunomodulators) can modulate specific nervous system function(s). Modulation of immune functions by neuroregulators has been receiving considerable attention; however, modulation of nervous system functions by immunomodulators has been little studied. The presence of immunomodulators in the brain and cerebrospinal fluid may represent local synthesis by astrocytes, microglia, endothelial cells, intrinsic macrophages and blood-derived lymphocytes which cross the blood-brain barrier, or the concentration of substances derived from the peripheral blood. Acute and chronic inflammatory processes, malignancy, and immunological reactions stimulate the synthesis and release of immunomodulators in various cell systems. These immunomodulators have pivotal roles in the coordination of the host defense mechanisms and repair and induce a series of endocrine, metabolic, and neurologic responses. This paper focuses on the effects of immunomodulators (interleukins, tumor necrosis factor, tuftsin, platelet activating factor, and others) on the central nervous system (CNS), in particular, on feeding regulation. It is proposed that an immunomodulatory system regulates food intake by a direct action in the CNS through a specific neuro-immuno interaction. This regulatory system may be operative during acute and chronic disease.